Electrical connector with continuous strip contacts

ABSTRACT

An electrical connector contact strip comprising spaced electrical contacts, a body and fusible elements. The spaced electrical contacts each have a main section and a tab section extending from an end of the main section. The body comprises dielectric material molded onto the contacts and connecting the contacts to each other. The fusible elements are mounted on the tab sections.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to electrical connectors and, moreparticularly, to a continuous strip of contacts secured in a housing toform an electrical connector.

[0003] 2. Brief Description of Earlier Developments

[0004] U.S. Pat. No. 3,500,295 discloses an electrical connector withterminals connected by an injection-molded elongate body which isembedded in a supporting structure. PCT publication No. WO 98/15989,herein incorporated by reference, discloses a high density electricalconnector with contacts having solder balls. A deformable element in anopening in the housing frictionally retains the contact.

[0005] A problem exists with conventional connectors in that solder canmove by wicking into a contact area of a contact, when the solder ismelted, which can interfere with a connection at the contact area.Another problem exists with conventional connectors in that differentsizes of connectors having different row lengths and array sizes requiredifferent tooling to manufacture. Another problem exists withconventional connectors in that effects of differential coefficient ofthermal expansion in a direction transverse to trip direction can causedamage to soldered connections. Another problem exists with conventionalconnectors in that tensile failures can occur in the connection of asolder ball to a contact. The present invention can help to overcomethese problems and provide other advantages.

SUMMARY OF THE INVENTION

[0006] In accordance with one embodiment of the present invention, anelectrical connector contact strip is provided comprising spacedelectrical contacts, a body and fusible elements. The spaced electricalcontacts each have a main section and a tab section extending from anend of the main section. The body comprises dielectric material moldedonto the contacts and connecting the contacts to each other. The fusibleelements are mounted on the tab sections.

[0007] In accordance with another embodiment of the present invention anelectrical connector is provided comprising a housing; and at least tworows of electrical connector contact strips connected to the housing.Each contact strip has electrical contacts connected to each other by abody comprising dielectric material. The contact strips are movablycaptured by their bodies in the housing.

[0008] In accordance with another embodiment of the present invention,an electronic component assembly is provided comprising a firstelectronic component comprising a printed circuit board; and anelectrical connector connected to the printed circuit board. Theelectrical connector comprises a housing and a plurality of contactstrips connected to the housing. The contact strips each comprisingelectrical contacts connected to each other by a body. The bodies aremovably captured in the housing such that the bodies can move relativeto each other.

[0009] In accordance with one method of the present invention, a methodof assembling an electrical connector is provided comprising steps offorming electrical contact strips, each strip comprising electricalcontacts connected to each other by a dielectric body; and mounting thestrips by their bodies to a housing, wherein the bodies are movablycaptured by the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The foregoing aspects and other features of the present inventionare explained in the following description, taken in connection with theaccompanying drawings, wherein:

[0011]FIG. 1 is an exploded partial cross-sectional elevational view ofan electronic assembly incorporating features of the present invention;

[0012]FIG. 2 is a partial perspective view of one of the contact stripsused in one of the electrical connectors shown in FIG. 1;

[0013]FIG. 3 is a cross-sectional view of the contact strip shown inFIG. 2 taken along line 3-3;

[0014]FIG. 4 is a perspective view of one of the connectors shown inFIG. 4;

[0015]FIG. 5 is a partial cross-sectional view taken along line 5-5 inFIG. 4;

[0016]FIG. 6 is a partial perspective view of the other one of thecontact strips shown in the second connector shown in FIG. 1;

[0017]FIG. 7 is a partial cross-sectional view of an alternateembodiment of the first electrical connector;

[0018]FIG. 8 is a perspective view of the housing of another alternateembodiment of the electrical connector;

[0019]FIG. 9 is a partial cross-sectional view of an alternateembodiment of the electrical connector using the housing shown in FIG.8;

[0020]FIG. 10A is a partial front elevational view of contacts attachedto a carry strip;

[0021]FIG. 10B is a partial front elevational view of the contacts shownin FIG. 10A with the body of a contact strip formed onto the contacts;

[0022]FIG. 10C is a partial front elevational view as in FIG. 10B withthe carry strip removed;

[0023]FIG. 11 is a partial perspective view of an alternate embodimentof the contact strip;

[0024]FIG. 12A is a cross-sectional view of an alternate embodiment ofthe electrical connector having contact strips as shown in FIG. 11; and

[0025]FIG. 12B is a cross-sectional view of the connector shown in FIG.12A taken along line 12B-12B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Referring to FIG. 1, there is shown an exploded elevational viewof an assembly 10 incorporating features of the present invention.Although the present invention will be described with reference to theembodiments shown in the drawings, it should be understood that thepresent invention can be embodied in many alternate forms ofembodiments. In addition, any suitable size, shape or type of elementsor materials could be used.

[0027] The assembly 10 generally comprises a first electronic componentassembly 12 and a mating second electronic component assembly 14. Inthis embodiment the first assembly 12 generally comprises a firstcircuit substrate, such as a printed circuit board 16 and a firstelectrical connector 18. The second assembly 14 generally comprises asecond circuit substrate, such as a printed circuit board 20 and asecond electrical connector 22. However, in alternate embodiments theconnectors 18, 22 could be attached to different types of electroniccomponents other than printed circuit boards. Referring also to FIGS.2-4, the first connector 18 generally comprises a housing 23 and stripsof contacts 26. Each strip defines a row of contacts. The housing 23 ispreferably comprised of molded plastic or polymer dielectric material,such as a liquid crystal polymer (LCP). In this embodiment the housing23 is comprised of two housing pieces 24, 25. However, in alternateembodiments the housing 23 could be comprised of only one or more thantwo pieces. In another alternate embodiment, the housing piece 24 mayinclude features, such as solder pads or standoffs (not shown), thathelp in mounting the housing to the first printed circuit board 16.However, any suitable means can be provided for attaching the housing tothe first printed circuit board. In this embodiment the housing piece 24has receiving areas 30 for receiving the contact strips 26. FIG. 4 showsonly one contact strip 26 in the receiving areas 30 merely for the sakeof clarity. In actual practice all the receiving areas 30 wouldpreferably have contact strips 26 located therein. In the embodimentshown, the housing piece 24 has five receiving areas 30 aligned parallelto each other as straight slots which extend entirely through thehousing piece 24 between the two sides 32, 34. However, in alternateembodiment any suitable number of receiving areas 30 could be provided.In this embodiment the receiving areas 30 can each hold a contact strip26 of four of the contacts 27. However, in alternate embodiments eachreceiving area 30 can hold any suitable number of contacts 27. As seenbest in FIG. 5, each receiving area 30 could have opposing inwardlyprojecting ledge 36 proximate the side 32. The second housing piece 25is attached to the first housing piece 24 and has areas 38 with thecontacts 27 therein for receiving portions of the contacts in the secondelectrical connector 22. However, in alternate embodiments any suitabletype of housing can be provided.

[0028] The contact strips 26 are adapted to be inserted into the housing23 in a modular assembly fashion. The strips 26 can each comprise a body40, the contacts 27, and formed bodies, such as solder balls 42. Thebody 40 is preferably a one-piece molded plastic or polymer member whichis preferably over-molded onto the contacts 27. However, in an alternateembodiment the body 40 could comprise multiple members and/or the body40 could be formed separate from the contacts 27 with the contacts 27being subsequently inserted into the body 40. Over-molding the body 40onto the contacts causes the body 40 to function as a seal between thetwo opposite sections 46, 48 of the contacts 27 to prevent solder fromthe solder ball 42 wicking up the contact 27 during a reflow operationused to secure the connector 18 to the printed circuit board 16. Thus, asuitable amount of solder is available to surface mount connector 18 andthe contact surface of the male contact section 46 is prevented frombeing contaminated by solder. Alternatively, contacts 27 could have anysuitable type of connection at the two end sections 46, 48. For example,the contacts 27 could have surface mount tails.

[0029] In a preferred method of manufacturing the strips 26, thecontacts 27 are connected to each other as a unitary contact blank. Thebody 40 is over-molded onto the contact blank. Then the contact blank iscut to remove connecting sections to thereby electrically isolate theindividual electrical contacts 27 from each other. However, the body 40maintains a structural connection among the contacts 27 in the strip 26.Preferably, the strips 26 are manufactured as a substantially continuousstrip which is rolled onto a reel and subsequently cut intopredetermined lengths of the contacts 27 for assembly into housings. Inan alternate method of manufacturing the contact strip the body could bepre-formed and the contacts could be inserted into the pre-formed body.

[0030] Each contact 27 is preferably stamped and formed from a sheet ofconductive material, such as copper alloy. Each contact has a centersection 44 and two end sections 46, 48. A first one of the end sections46 extends from the body 40 and forms a contact area, such as theblade-type contact area shown in FIG. 2, or the dual beam contact shownin FIG. 6, or any other suitable arrangement. The second end section 48extends from the opposite end of the body 40 and could have a solderball mounting tab for mounting the solder ball 42 to the contact 27.When using a solder ball, the tab 48 can have a dovetail shape with twopockets 50 between the tab 48 and the center section 44. The material ofthe solder ball 42 extends into the pockets 50 to retain the solder ball42 on the contact 27 prior to mounting of the connector 18 to the firstprinted circuit board 16. However, other shapes of the contacts 27 andother features could be provided.

[0031] The body 40 generally comprises main sections 52 andinterconnecting sections 54. The main sections 52 surround individualones of the center sections 44 of the contacts 27. The contacts 27include notches 47 in the center section 44. When the body 40 is moldedonto the center section 44 the material of the body 40 extends into thenotches 47. This forms an interlocking of the contacts 27 to the body 40to retain the contacts with the body. However, any suitable system forconnecting the contacts with the body could be provided. Theinterconnecting sections 54 connect the main sections 52 of each strip26 to each other in series. In one embodiment, the main sections 52comprise tapered top edges 56. The main sections 52 are sized and shapedto very closely fit inside the receiving areas 30. Alternatively, strip26 could be interference fit within receiving areas 30. The top edges 56interact with the ledges 36 to retain the body 40 with the housing piece24 prior to mounting the first connector 18 to the first printed circuitboard 16. The interconnection sections 54 are smaller than the mainsections 52 and are adapted to both space the main sections 52, andtheir respective contacts 27, from each other in each strip 26 at fixedlocations and, allow for relatively easy cutting or severing of theinterconnection sections 54 to form the multiple strips 26 from a reelof a relatively long single contact strip. In alternate embodiments themain sections 52 and interconnection sections 54 could have any suitableshape. Alternative and/or additional means could also be used toassemble the contact strips 26 with the housing piece 24.

[0032] Referring now to FIGS. 1 and 6, the second electrical connector22 generally comprises a second housing 60 and electrical connectorcontact strips 62. The second housing 60 has slots 64 therethrough whichfunction as receiving areas for the contact strips 62 similar to thereceiving areas 30 in the first housing piece 24. The second housing 60is adapted to be fixedly connected to the second circuit substrate, suchas a printed circuit board 20. The second housing 60 has a perimeterwall that defines a receiving area 66 for aligning and receiving aportion of the first connector 18 therein. The contact strips 62 eachgenerally comprise a frame 68, electrical contacts 70 and formed bodies,such as solder balls 72. The frame 68 is substantially the same as theframe 52. The solder balls 72 are substantially the same as the solderballs 42. The electrical contacts 70 generally comprise two deflectablearms 74 which form mating area for receiving the first end section 46 ofthe first contacts 27. The arms 74 are sized and shaped to fit insidethe areas 38 of the first connector's housing 25, if used. The contactstrips 62 and housing 60 are connected to each other similar to thecontact strips 26 and housing piece 24.

[0033] This design concept over molds a continuous strip of contactsthat have a solder ball soldering attachment on one end and a matingconfiguration on the other. The strip is produced on a matching pitch B.The strips are cut to any desired length to construct a series of rowsto form an array that is positioned by another member that would holdthem in position to form this configuration. This design eliminatessolder wicking into the contact area by the over molded sectionseparating the two areas. This design provides flexibility forconfiguring various row lengths and array sizes. For example, the sametype contact strip can be used with different size housings merely bycutting the contact strip to different lengths such as for housings forholding strips of 8, 10, 20, 30, or 40 contacts each. This designreduces the tooling cost for producing multiple sizes by utilizing onecomponent to produce many variations of sizes. This design is highlyautomatable in the form of a continuous strip for significant costsavings. This design de-couples the effects of differential co-efficientof thermal expansion (CTE) in the direction transverse to stripdirection by utilizing rows of terminals to construct an arrayconfiguration making. the construction of large arrays feasible. Thelarger the size of the connector, the larger the differential CTE. Bydecoupling the contacts 27, 70 in direction A, with the contacts beingable to partial move or float relative to their frames, the differentialCTE among the various components can be accommodated to prevent damageto the soldered connections to the printed circuit boards. This designcan incorporate a ball tab feature that resist solder ball tensilefailures.

[0034] Referring now to FIG. 7 a partial cross-sectional view of analternate embodiment of the connector is shown. In this embodiment theconnector 100 includes a housing 102 and contact strips 104 (only one ofwhich is shown) captured by the housing 102. The housing 102 generallycomprises two housing pieces 106, 108. The contact strips 104 generallycomprise contacts 110, body 112, and formed bodies, such as solder balls114. The contacts 110 and solder balls 114 are substantially the same asthe contacts 27 and solder balls 42. The main sections 116 of the body112 are substantially the same as the main sections 52, but have taperedtop and bottom edges 118, 119. The housing pieces 106, 108 have inwardlyprojecting ledges 120, 121 at lateral sides of the receiving slots 122to capture the body 112 in the slots. The spacing between the lateralsides of the body 112 and the housing pieces at the slots 122 is suchthat the body 112 and their contacts 110 can slightly laterally move asindicated by arrow A.

[0035] Referring now to FIGS. 8 and 9 another alternate embodiment willbe described. In this embodiment the connector 200 has a housing 202with two pieces 204, 206 that have an enlarged receiving area 208 sizedand shaped to receive more than one contact strip. In this embodimentthe connector 200 has two different types of contact strips 210, 212.The contact strips 210, 212 have the same type of contacts 214 andsolder balls 216, but their frames or bodies 218, 220 have differentshapes. More specifically, the main sections of the bodies 218, 220 aresized and shaped to mate with each other as shown. The bodies 218 aresubstantially the same as the bodies 112, but the bodies 220 haveoutwardly projecting ledges 222 on its top and bottom sides such thatthe bodies 218, 220 cooperate to capture each other within the receivingarea 208. In an alternate embodiment each contact strip could havealternating types of the bodies 218, 220.

[0036] Referring now to FIGS. 10A, 10B and 10C, one method ofmanufacturing a contact strip will be described. In this method, as seenin FIG. 10A, the contacts 27 are formed from a sheet 300 of conductivematerial. The sheet 300 has been stamped and formed to provide a carrystrip 302 that connects the contacts 27 to each other. The body,including interconnection sections 54, is then over-molded onto thecontacts 47 as shown in FIG. 10B. As seen in FIG. 10C, the carry strip302 is then removed from the contacts 27. The contacts 27 are, thus,spaced from each other and electrically isolated from each other. Thebody 40 maintains the structural relationship of the contacts 27relative to each other after the carry strip 302 is removed.

[0037] Referring now to FIG. 11, an alternate embodiment of the contactstrip 26 is shown. In this embodiment the contact strip 310 generallycomprises contacts 27, a body 314, and fusible elements 42, such assolder balls. The body 314 generally comprises main sections 312 andinterconnecting sections 314. The main sections 312 include a lateralprojection 316 on one side 318 and a lateral recess 320 on an oppositeside 322. Referring also to FIGS. 12A and 12B, a plurality of thecontact strips 310 are shown connected to each other and with a housing324 to form a connector 326. The lateral projections 316 and recesses320 are sized and shaped to mate with each other to connect the strips310 to each other. In alternate embodiments any suitable shape of matingconnection between the strips could be provided. In this embodiment thehousing 324 includes a receiving area 328 to receive the strips 310. Thehousing 324 includes a projection 330 at one side of the receiving area328 and a recess 332 at an opposite side of the receiving area. Theprojection 330 extends into the recesses 320 of one of the strips 310.The recess 332 receives the projections 316 of another one of the strips310. Thus, the interlocking of the projections 316, 330 with therecesses 320, 332 connect the strips 310 with each other and the housing324. With this type of embodiment the strips 310 are not substantiallyconstrained in the plane shown in FIG. 12B.

[0038] It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from theinvention. Accordingly, the present invention is intended to embrace allsuch alternatives, modifications and variances which fall within thescope of the appended claims.

What is claimed is:
 1. An electrical connector contact strip comprising:spaced electrical contacts, each contact having a main section and a tabsection extending from an end of the main section; a body comprisingdielectric material molded onto the contacts and connecting the contactsto each other; and fusible elements mounted on the tab sections.
 2. Acontact strip as in claim 1 wherein each tab section has an outwardlyflared shape.
 3. A contact strip as in claim 1 wherein the fusibleelements have portions located in the pocket areas of the contacts toretain the fusible elements on the tab sections.
 4. A contact strip asin claim 1 wherein the tab sections extend from a first side of the bodyand a second end section of the contacts extend from an opposite secondside of the body.
 5. A contact strip as in claim 4 wherein the bodyforms a seal between the tab sections and the second sections to preventwicking of the fusible elements along the contacts between tab sectionsand the second sections.
 6. A contact strip as in claim 4 wherein thesecond sections comprise male contact tab sections.
 7. A contact stripas in claim 4 wherein the second sections comprise deflectable contactsections.
 8. A contact strip as in claim 1 wherein the body comprisesmain portions surrounding the main sections of each contact and smallerinterconnecting sections connecting the main portions to each other. 9.A contact strip as in claim 1 wherein the contacts are connected to eachother by the body in series in a single row.
 10. An electrical connectorcomprising: a housing; and at least two rows of electrical connectorcontact strips connected to the housing, each contact strip havingelectrical contacts connected to each other by a body comprisingdielectric material; wherein the contact strips are movably captured bytheir bodies in the housing.
 11. An electrical connector as in claim 10wherein the housing comprises rows of receiving areas for receiving thecontact strips.
 12. An electrical connector as in claim 11 wherein thereceiving areas include inwardly projecting flanges at a top side of thehousing.
 13. An electrical connector as in claim 10 wherein the housingcomprises at least two members, and wherein the contact strips aresandwiched between portions of the two members to movably capture thecontact strips in the housing.
 14. An electronic component assemblycomprising: a first electronic component comprising a printed circuitboard; and an electrical connector connected to the printed circuitboard, the electrical connector comprising a housing and a plurality ofcontact strips connected to the housing, the contact strips eachcomprising electrical contacts connected to each other by a body,wherein the bodies are movably captured in the housing such that thebodies can move relative to each other.
 15. An assembly as in claim 14wherein the electrical contacts have first ends extending from theirbodies which are soldered to the first electronic component.
 16. Anassembly as in claim 15 wherein the first ends have pockets forretaining fusible elements on the first ends prior to mounting theelectrical contacts to the first electronic component.
 17. An assemblyas in claim 15 wherein the contacts have second ends extending fromtheir bodies and wherein the bodies are comprised of dielectric materialmolded over the contacts which seals the contacts between the first andsecond ends of the respective contacts.
 18. A method of assembling anelectrical connector comprising steps of: forming electrical contactstrips, each strip comprising electrical contacts connected to eachother by a dielectric body; and mounting the strips by their bodies to ahousing, wherein the bodies are movably captured by the housing.
 19. Amethod as in claim 18 wherein the step of forming the contact stripsincludes providing the contacts with mounting tabs having a pocket, andmounting fusible elements on the tabs.
 20. A method as in claim 18wherein the step of mounting comprises capturing the bodies betweenportions of the housing.